Prioritize cash-out flow based on market research (95%+ activity)

Market context added:
- 95%+ activity is cash-out (selling Bitcoin for cash)
- Typical for remittance corridors, Bitcoin-paid workers
- Bill dispenser is REQUIRED for testing, not optional

Updated development priorities:
- Cash-out first, cash-in second
- Dispenser in minimum dev kit (~$655-855)
- Bill validator becomes secondary priority

Updated milestones:
- Priority 1: Cash-out with real dispenser
- Priority 2: Cash-in (mock validator OK initially)
- Priority 3: Advanced features (Cashu, etc.)

Phase 4 reorganized to implement cash-out before cash-in.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/implementation-plan.md

@@ -29,13 +29,28 @@ priority: critical
 
 ---
 
+## Target Market Context
+
+> [!important] Cash-Out Dominant Market
+> Market research shows **95%+ of activity is cash-out** (users selling Bitcoin for cash). This is typical for:
+> - Remittance corridors (receiving Bitcoin from abroad)
+> - Bitcoin-paid workers converting to local currency
+> - Merchants liquidating Bitcoin revenue
+>
+> **Implications:**
+> - Bill dispenser is **essential** for testing, not optional
+> - Cash-out flow is the **critical path**
+> - Cash-in still important (equal weight in code) but secondary for go-live
+
+---
+
 ## Guiding Principles
 
 > [!important] Build Philosophy
-> 1. **Vertical slices** - Each phase delivers working functionality
+> 1. **Cash-out first** - Primary use case, test with real dispenser early
-> 2. **Test on real hardware early** - Don't wait until "everything is ready"
+> 2. **Vertical slices** - Each phase delivers working functionality
-> 3. **Mock what you must** - But prefer real components when possible
+> 3. **Test on real hardware early** - Dispenser essential, not optional
-> 4. **Ship incrementally** - Working ATM with 1 bill validator > perfect ATM with 10
+> 4. **Ship incrementally** - Working cash-out ATM > feature-complete vaporware
 
 ---
 
@@ -1436,7 +1451,13 @@ console.log(`Dispensed ${dispensed} bills`)
 ## Phase 4: Payment Flows
 
 > [!goal] Deliverable
-> Complete cash-in and cash-out flows working end-to-end.
+> Complete cash-out (primary) and cash-in flows working end-to-end.
+
+> [!important] Cash-Out First
+> Given 95%+ cash-out activity in target market:
+> 1. **4.2 Cash-Out** - Implement and test first
+> 2. **4.3 Cash-In** - Implement second
+> 3. Both flows share Lightning.Pub integration
 
 ### 4.1 Lightning.Pub Integration
 
@@ -1589,14 +1610,23 @@ export class ATMCashuWallet {
 
 ### 4.5 Milestone Checklist
 
+**Priority 1: Cash-Out (95% of volume)**
 - [ ] Lightning.Pub client connects
-- [ ] Can create invoices
+- [ ] Can create invoices (for user to pay)
-- [ ] Can receive payments
+- [ ] Invoice payment detection working
-- [ ] Cash-in flow works end-to-end (mock hardware)
+- [ ] Dispenser integration (real hardware!)
-- [ ] Cash-out flow works end-to-end (mock hardware)
+- [ ] Cash-out flow works end-to-end with real dispenser
+- [ ] NFC BOLT card tap-to-withdraw working
+
+**Priority 2: Cash-In**
+- [ ] Can receive payments (CLINK debit)
 - [ ] CLINK offer request/response working
+- [ ] Cash-in flow works end-to-end (mock validator OK)
 - [ ] NIP-17 receipts delivered
+
+**Priority 3: Advanced**
 - [ ] Cashu offline mode works
+- [ ] Real bill validator integration
 
 ---
 
@@ -1725,28 +1755,31 @@ export function useFleet() {
 
 ## Development Hardware
 
-### Recommended Dev Kit (One-Way: Cash-In Only)
+> [!warning] Cash-Out is Primary Use Case
+> With 95%+ activity being cash-out, **bill dispenser is required** for meaningful testing - not optional.
+
+### Minimum Dev Kit (Cash-Out Priority)
 
 | Component | Model | Purpose | Est. Cost |
 |-----------|-------|---------|-----------|
 | SBC | Raspberry Pi 5 (8GB) | Development machine | $80 |
-| Display | Waveshare 7" touch | UI development | $70 |
+| Display | Waveshare 10.1" touch | UI development | $90 |
-| Bill Validator | ITL NV200 (used) | Real hardware testing | $300-500 |
+| **Bill Dispenser** | Puloon LCDM-1000 (used) | **Cash-out testing (critical)** | $400-600 |
+| NFC Reader | ACR122U | BOLT card tap-to-withdraw | $35 |
 | Printer | Generic ESC/POS | Receipt testing | $50 |
-| NFC Reader | ACR122U | BOLT card testing | $35 |
+| **Total** | | | **~$655-855** |
-| **Total** | | | **~$535-735** |
 
-### Full Dev Kit (Two-Way: Cash-In + Cash-Out)
+### Full Dev Kit (Two-Way)
 
 | Component | Model | Purpose | Est. Cost |
 |-----------|-------|---------|-----------|
 | SBC | Raspberry Pi 5 (8GB) | Development machine | $80 |
 | Display | Waveshare 10.1" touch | Larger UI for two-way | $90 |
-| Bill Validator | ITL NV200 (used) | Cash-in acceptance | $300-500 |
+| **Bill Dispenser** | Puloon LCDM-1000 (used) | Cash-out (primary) | $400-600 |
-| **Bill Dispenser** | Puloon LCDM-1000 (used) | Cash-out dispensing | $400-800 |
+| Bill Validator | ITL NV200 (used) | Cash-in (secondary) | $300-500 |
-| Printer | Generic ESC/POS | Receipt testing | $50 |
 | NFC Reader | ACR122U | BOLT card testing | $35 |
-| **Total** | | | **~$955-1,555** |
+| Printer | Generic ESC/POS | Receipt testing | $50 |
+| **Total** | | | **~$955-1,355** |
 
 ### Bill Dispenser Options
 
@@ -1757,7 +1790,15 @@ export function useFleet() {
 | Fujitsu F53 | 4 | 2,500 notes | USB/RS-232 | $800-1,200 |
 
 > [!tip] Start with Puloon LCDM-1000
-> Single cassette is sufficient for development. Simple RS-232 protocol with existing lamassu-machine drivers to reference.
+> Single cassette handles the primary use case. Multi-cassette (for multiple denominations) can come later.
+
+### Bill Validator Options (Secondary Priority)
+
+| Model | Protocol | Notes | Est. Used Price |
+|-------|----------|-------|-----------------|
+| **ITL NV200** | eSSP | Industry standard, good docs | $300-500 |
+| MEI Cashflow | ccTalk/MDB | Common in NA market | $250-400 |
+| JCM iVizion | ID-003 | Existing lamassu driver | $200-350 |
 
 ### Sourcing Used Equipment
 
@@ -1765,10 +1806,11 @@ export function useFleet() {
 - **Alibaba** - New units, but longer shipping
 - **ATM parts suppliers** - atmpartsnow.com, atmequipment.com
 - **Bitcoin ATM operators** - Sometimes sell retired units
+- **ATM route liquidations** - Best prices, bulk deals
 
 ### Mock-First Development
 
-For most development, mocks are sufficient:
+For initial UI/flow development, mocks work - but **test with real dispenser early**:
 
 ```typescript
 // Start with mocks